As a process for removing an oxygen compound, as an impurity, which is present in a fluorine compound to purify this compound, there has been hitherto given a method of adding an anhydrous hydrogen fluoride solution to a fluorine compound and repeating the steps of crystallization, solid-liquid separation and drying (see, for example, Patent Documents 1 and 2) a few times. However, the anhydrous hydrogen fluoride solution used in the process is very dangerous, and fastidious care and experience are required. Thus, the process is poor in handleability. Furthermore, this process has a problem that producing costs and the number of steps increase.
Given is also a method of decreasing an oxygen component or carbon component present in a fluorine compound by a fluorine gas (see, for example, Patent Document 3). However, the fluorine gas used in the process is very dangerous, and fastidious care and experience are required. Furthermore, this process includes problems that this process is limited to a case where the fluorine compound is powdery, the process is carried out only at room temperature or higher, and the like.
Patent Document 1: JP-A-05-4801
Patent Document 2: JP-A-09-268005
Patent Document 3: JP-A-2002-241196